B cells are required for the host protection to the gastrointestinal nematode parasite Heligmosomoides polygyrus

Previous studies from our laboratory have shown an important role for B cells in the development of Ag‐specific Th2 cells during a polarized Th2‐type response. In this study we examined the role of B cell in host protection to a nematode parasite, Heligmosomoides polygyrus (Hp). Hp is characterized by chronic infection following primary inoculation, but following drug‐induced worm clearance, secondary inoculation triggers a host protective memory Th2‐type response resulting in worm clearance. B cell deficient JhD and control WT mice were orally inoculated with Hp, followed by anti‐helminthic drug treatment on day 14, and one month later challenged with Hp. Compared to WT mice, JhD mice were much more susceptible to Hp infection with high numbers of worms. B cell deficiency did not affect T cell activation, IL‐4 and IL‐13 production by CD4 T cells in mesenteric lymph nodes, and alternatively activated macrophage activation in granulomas surrounding developing larvae in the submucosa. However, immunofluorescent staining of granulomas showed that there were more Gr‐1 + neutrophils adjacent to the parasites, and less Gr‐1 + F4/80 + cells surrounding these Gr‐1 + cells in JhD mice compared to WT mice. These results suggest that B cells are required for the development of an effective memory response culminating in parasite expulsion.